This invention relates to a rotation transmission device used for switching transmission and blocking of driving torque in a power transmission path.
The device disclosed in JP Patent Publication 2007-247713A is known as a device of this type. As shown in FIG. 5A, this rotation transmission device comprises a housing 50 having an end wall 51 in which a shaft hole 52 is formed, an input shaft 53 inserted through the shaft hole 52 into the housing 50, an inner ring 54 coupled to the end of the input shaft 53, an outer ring 55 provided around the inner ring 54, a two-way roller clutch 60 mounted between the inner ring 54 and the outer ring 55 for transmitting and blocking torque therebetween, and an electromagnetic clutch 70 provided adjacent to the two-way clutch 60 for controlling engagement/disengagement of the two-way roller clutch 60.
The two-way roller clutch 60 comprises cam surfaces 62 formed on the outer-diameter surface of the inner ring 54, defining wedge-shaped spaces between the respective cam surfaces 62 and a cylindrical surface 61 formed on the inner-diameter surface of the outer ring 55, rollers 63 mounted between the respective cam surface 62 and the cylindrical surface 61, a retainer 64 mounted between the inner ring 54 and the outer ring 55 for retaining the rollers 63, and a switch spring 65 biasing the retainer 64 to a neutral position, where the rollers 63 are disengaged from the cam surfaces 62 and the cylindrical surface 61.
The electromagnetic clutch 70 comprises an armature 71 which is rotationally fixed but axially movable relative to the retainer 64, a rotor guide 72 connected to the outer ring 55, a rotor 73 mounted in the rotor guide 72 and axially facing the armature 71, an electromagnet 74 axially facing the rotor 73, and a separation spring 75 biasing the armature 71 away from the rotor 73. When the electromagnet 74 is energized the armature 71 is attracted to and contacts the rotor 73. This causes the armature 71 to rotate relative to the inner ring 54 to thereby bring the rollers 63 into engagement with the cylindrical surface 61 and the cam surfaces 62.
In this rotation transmission device, a clearance between the inner-diameter surface of the shaft hole 52 and the outer-diameter surface of the input shaft 53 is sealed by a seal member 56 attached to the inner-diameter surface of the shaft hole 52, and a clearance between the end of the opening of the housing 50 and the outer-diameter surface of the outer ring 55 is sealed by a seal member 57 so that foreign material does not come into the housing 50.
The inner ring 54 and the outer ring 55 are supported so that they can rotate relative to each other by a bearing 58 fitted on the outer-diameter surface of the inner ring 54 at its end near the open end of the housing. The outer ring 55 is rotatably supported by a bearing 59 attached to the inner-diameter surface of the housing 50.
In the rotation transmission device disclosed in JP Patent Publication 2007-247713A, the bearing which supports the inner ring 54 and the outer ring 55 so that they can rotate relative to each other, and the two-way roller clutch 60 are lubricated with greases of different qualities. To prevent these greases from being mixed with each other and from being leaked out, the bearing 58 has two seals on both sides.
The bearing 59 supporting the outer ring 55 so as to be rotatable relative to the housing 50 is, as shown in FIG. 5B, mounted adjacent to the rotor guide 72. A labyrinth 76 is formed between the ends of the bearing 59 and the rotor guide 72. The labyrinth 76 prevents lubricating grease from leaking out from the inner end of the bearing 59. However, since there is no other means to prevent the grease from leaking out of the bearing 59 from the end near the opening of the housing, the bearing 59 has to have a seal on this side.
Thus in the conventional rotation transmission device, since the bearings 58 and 59 both have at least one seal, rotation resistance and energy loss are large, and the cost is high.
An object of this invention is to provide a rotation transmission device with smaller energy loss and lower cost.